Setting dataset instance properties through CLI is confusing.

Details

Improved and clarified certain of the CDAP CLI help text and its error messages.

Rank:

1|hzzhjr:

Description

Setting dataset instance properties through CLI is confusing:
1. When we get dataset instance properties we get them JSON format, so user might expect to use the JSON while setting properties through CLI.
2. We need to add documentation to the command explaining the format of the properties that should be provided. Currently we accept them in "key1=value1 key2=value2" format.
3. When invalid properties are provided, we get following message